Avatar Height x Width:
Registered Users: 150 x 200 pixels
Moderators: 170 x 220

Avatar Filesizes:
Registered Users: 34kb
Moderators: 54kb

Signature Height x Width:
Registered Users: 600 x 200
Moderators: 600 x 250

Signature Filesize:
Registered Users: 75kb
Moderators: 78kb